Turbine.



PATENTBD 0012-8, 1907.

NBAASHUUS,

TURBINB.

l Y APpLIoATIoN PLLED 11u25. 19o?.

' running-wheel of an axial turbine, aa being the outer NlLS BAASHUUS,OF CHRISTIANIA, NORWAY.

TURB INE Specification of Letters Patent.

Patented Oct. 8, 1907.

Application filed. May 25,1907. Serial No. 375,604.

gas) can be very thoroughly utilized with varying discharges.

The invention is illustrated in the accompanying drawing.

Figure l is asection through a portion of the runningwheel of an axialturbine. Figs. 2-5 are diagrams explanatory of the nature of theinvention with respect to axial turbines. Fig. 6 is a section through aportion of the running-wheel of a radial turbine. Figs. 7 and 8 arediagrams explanatory of the nature of the invention with respect toradial turbines.

Referring more particularly to Figs. 1 5, A is the and it' the innerlimit of the buckets. r,L and ri are the corresponding radii. Ifthewheel A is cut in cylindrical surfaces concentric with the axis ofthe turbine and these sections are laid out in the plane of the drawing,the bucket curve is arrived at. The bucket sections at aaand it' of Fig.l are represented at a-a and i in this manner (Fig. 2), the insidewidths of exit at the outer and inner limits respectively being seen atW,L and Wi. The angles ga, g, are the angles of exit, which determinethe loss in outow. The variation in the inside widths of exit with theradii of the exit edge is seen in the diagram Fig. 3, where the breadthb of the buckets is employed as abscissa and the inside widths of exitas ordinates. From Fig. 3 it is obvious that theinside widths of exitincrease with increasing radius, which. in turbines of priorconstruction is the case.

According to my invention, by selection of the dimensions of the anglesof exit g/a and gi, the inside widths of exit are such lthat the minimumof the same lies in the outer quarter of the exit edge, as` shown inFig. 4, where afa and 1"-.1' represent the bucket sections at aa and'it' of Fig., l, WQ, and W/i being the new widths of exit. The variationof these widths of exit with the radii o the exit edge is shown by wayof example inthe diagram Fig. 5. That such dimensions for the insidewidths of exit are possible is clear when it is remembered thattheinside width of exit is a .and 5. kWidths of exit.

product of t,L (or t1), Fig. 2, and the sine oi the angle g,l (or gi),that is, expressed in general terms The influence of the thickness ofthe buckets can here be neglected. In this expression the factor tx witha given number of buckets is to be regarded as given, and the angle gXmay be given various values depending upon the principle ofconstruction. According to my invention the angles gX are given suchlvalues that the inside widths of exit at the outer circumference (W) aresmaller than those at the inner circumference (Wfl) and that the minimumof the inside widths of exit lies in the outer quarter of the exit edge.

The principle, above set forth with reference to axial turbines, of theminimum of the inside widths of exit lying in the outer quarter of theexit edge can also be applied to radial turbines. In Fig. 6, B is therunningwheel of a radial turbine, aa being the outer and 'it' the innerlimit of the buckets. The exit edge is indicated by b and one of thecenter points of the same by m. In Fig. 7 the exit edge is shown laidout as a straight line in the plane of the drawing and used as abscissaof a diagram similar to those shown in Figs. 3 The ordinates are thecorresponding inside variations of the widths of exit as hithertoadopted along the exit edge. Curve I shows that the width of The curvesI, II, III, IV show the exit from the outer limit (at a) decreasesinwardly (toward i). Curve II shows that it is made constant along theexit edge. Curve III shows that it decreases both from outside andinside toward a point near the middle (at m). Curve IV shows that itincreases both from the outer limit and from the inner limit toward themiddle.

According to my invention the inside exit-widths by selection of thedimensions of the angles of exit are such that the Vminimum of the samelies in the outer quarter of the exit edge, as shown in the four curvesof Fig. 8. That this is possible follows from what has been said inrespect to axial turbines. By reason of such distribution of the area ofexit the working agent with varying discharges is particularly wellutilized. For with a smaller discharge, by reason of the decrease of`the degree of reaction and the relative velocity of iniiow, theincreasing infiuence of the centrifugal force compels the working agentto flow out chiefly at the places of exit lying radially furthest fromthe axis of rotation, that is to say, at. the places that is, in the l0eI'Iiciency than those hitherto constructed.

Having thus described my invcniion, what l chiim as new and desire tosecure hy Letters Pnicnt is* In :1 turbine, :i running-dicci in whichthe minimum o1' thc inside widths of exit lics in (Init qunricr o1' ihchnflih of the exit odge which is most; remote from Ihe :lxis 11"15rotation, suhstnntinily :is und for iin` pnl-poses sul, forth.

In witness whereof 1 have lnrcnnto svt my hund in presence of twowtncsscs.

NILS i.\.\SIlIiliS. Witnesses Wonnmmn HAUPT, I'InNnY H isi'nn.

